A quite well documented problem is the HTTP 500 Internal Server Error in SharePoint or Project Server. This can happen with Claims Based Authentication.
An exception occurred when trying to establish endpoint for context: An error occurred loading a configuration file: Either a required impersonation level was not provided, or the provided impersonation level is invalid.
To resolve this, I normally look to the following;
- Click Start > Administrative Tools > Local Security Policy > Local Policies > User Rights Assignments
- Select Impersonate a client after authentication properties
- Ensure IIS_IUSRS and the Farm Admin account is added, assuming not, add them
- GPUPDATE / FORCE
- REBOOT (This is the stepe most online material fails to mention, its essential)
Failing that, it maybe worth checking the ‘logon as batch job’ as well.